Problem: Multiply.
Explanation: First, let's rewrite $3\dfrac12$ as a fraction. Then, we can multiply. $\phantom{=} 3\dfrac{1}{2} \times 3\dfrac12$ $ = ~\dfrac{7}2 \times \dfrac{7}2$ $ $ [How do we write a mixed number as a fraction?] $=\dfrac{7\times 7}{2 \times2}$ $=\dfrac{49}{4}$ The product, in lowest terms, is $\dfrac{49}{4}$. We can also write this as $12\dfrac1{4}$.